Apparatus for forming hot top liners



April 22, 1969 F, EASTWOOD O 3,439,734

APPARATUS FOR FORMING HOT TOP LINERS Original Filed Dec. 6, 1965 Sheetof 2 Ff g April 22, 1969 F. EASTWOOD 3,439,734

APPARATUS FOR FORMING HOT TOP LINERS Original Filed Dec. 6. 1965 Sheet 2of 2 I N VENTOR ig FRED EAs'rwooo $21. W MM United States Patent3,439,734 APPARATUS FOR FORMING HOT TOP LINERS Fred Eastwood, FairviewPark, Ohio, assignors, by mesne assignments, to Foseco Trading A.G.,Graubunden, Switzerland, a Swiss company Original application Dec. 6,1965, Ser. No. 511,793, now Patent No. 3,384,149, dated May 21, 1968.Divided and this application Dec. 8, 1967, Ser. No. 714,378

Int. Cl. B22c 17/00, 9/12, 15/00 US. Cl. 164-213 2 Claims This inventionrelates generally to the art of hot topping and, more particularly, toimproved method and apparatus for cyclically forming heat-insulatingliners in a plurality of reusable hot top casings used for castingbig-end-up ingots.

This application is a divisional of my copending application Ser. No.511,793, filed Dec. 6, 1965, now Patent No. 3,384,149.

In the casting of metal ingots, it is common practice to use a hot topmounted on or at the top of an ingot mold for the purpose of containingfeed or head metal and maintaining it molten while the metal in theingot mold is solidifying. The metal in the hot top is above and incontact with the metal in the ingot mold so that as the metal in theingot mold shrinks, the feed metal feeds down into the ingot body andthus prevents the formation of shrinkage cavities in the body of theingot.

The latest type of hot top in commercial use for the casting ofbig-end-up ingots today comprises a single metal casing, preferably inthe form of a one-piece, casting, and a heat-insulating liner on theinner surface of the casing. The casing itself is reusable, but theinsulating liner must be replaced after each use, i.e. after the castingof each ingot. The liner is generally made of a relatively low costcomposition having good heat-insulating properties, the compositionbeing preformed in selfsupporting slabs or sleeves shaped to fit theparticular casing in which they are to be used. Then after each use ofthe hot top, the remnants of the used liner, which usually disintegratesduring the casting operation, are removed from the metal casing andreplaced by a new preformed liner.

When the heat-insulating liners are preformed in the shape of individualslabs, a typical relining operation consists of driving four slabs downalong the four inside walls of the casing with the slabs being wedgedagainst each other in the corners of the casing so as to urge the slabsagainst the casing walls. This method is described in more detail incopending application Serial No. 389,656, entitled Hot Top forBig-End-Up Ingot Molds, filed Aug. 14, 1964, and assigned to theassignee of this invention. While this method is a vast improvement overprior hot topping methods, it is still a time-consuming operation. Therelining operation can be carried out more efficiently when the liner ispreformed as a single sleeve which is simply inserted in the casing,rather than a plurality of slabs (also described in the aforementionedcopending application) but the adoption of this method on any largescale requires objectionably large storage facilities for the one-piecepreformed liners. In addition, the one-piece preformed liners areconsiderably more costly to ship. It will be appreciated that theseincreased space requirements for shipping and storing the one-pieceliners are due to the large waste space inside the liner sleeves.Moreover, since the one-piece liners are generally not tapered to anysubstantial degree, it is not even possible to telescope the liners tominimize the wasted interior space.

It is, therefore, a primary object of the present invention to providean improved hot topping method and apparatus which is extremely rapidand which does not 3,439,734 Patented Apr. 22, 1969 require anysubstantial storage space. More particularly, it is a main object ofthis invention to provide an improved method and apparatus for formingheat-insulating liners in hot top casings for use on bigend-up ingotmolds without time-consuming assembling operations and with only minimalshipping and storage costs. Stated another way, it is an object of thisinvention to provide an improved method and apparatus for reliningreusable hot top casings in a minimum turn-around time and withoutshipping and storing bulky preformed liners.

It is another object of this invention to provide a method and apparatusof the type described above which can be carried out automatically withlittle or no manual labor. In this connection, a related object of theinvention is to provide such a method and apparatus which greatlyreduces overall hot topping costs.

A further object of the present invention is to provide an improvedmethod and apparatus for relining reusable hot top casings which permitssignificant reductions in the cost of the lining composition. A relatedobject is to provide such a hot topping method and apparatus whicheliminates the need for the heat-insulating liner composition to beself-supporting, and thus does not require any costly resin or similarexpensive binder material. Another related object is to provide such ahot topping method and apparatus in which it is not critical to remove asufficient quantity of water or other carrier liquid to render the linerself-supporting. As used herein, the term self-supporting refers to aliner which is capable of supporting itself and being handled when it isnot engaging any supporting structure whatever.

A still further object of the invention is to provide an improved methodand apparatus for relining reusable hot top casings which eliminates theneed for a substantial resin content to prevent moisture pick-up in theliner. In this connection, a corollary object is to provide such amethod and apparatus which do not involve critical temperatures, becausetemperature critical resins are not required.

Yet another object of the invention is to provide an improved hottopping method and apparatus which eliminates losses due to breakage ofpreformed liners during shipping, storage and assembling operations.

It is a further object of the present invention to provide an improvedhot top relining method and apparatus which permits the elimination ofspring clips and other supplementary devices for retaining the liner inthe hot top casing. Thus, a related object is to provide such a methodand apparatus which obviates clip holes in the hot top casing and,therefore, eliminates the problem of metal clogging in such holes.

It is still another object of this invention to provide an improved hottopping method and apparatus of the foregoing type which permits therelining of hot top casings of different configurations without carryinga separate stock of preformed liners for each different casingconfiguration.

Other objects and advantages of the invention will become apparent fromthe following description and upon reference to the accompanyingdrawings, in which:

FIGURE 1 is a perspective view of a hot top constructed in accordancewith this invention, with one corner of the hot top being broken away toshow the internal structure;

FIG. 2 is an end view, partially in section, of a mechanism for formingthe insulating liner in the hot topof FIGURE 1; and

FIG. 3 is a side elevation, partially in section of the mechanism ofFIG. 2.

While the invention is described in connection with certain preferredembodiments, it will be understood that 3 it is not thereby intended tolimit the invention to those embodiments. On the contrary, it isintended to cover all alternatives, modifications and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims.

Turning now to the drawings, in FIGURE 1 there is shown a hot topadapted to be mounted on the top of a big-end-up ingot mold, such asused in the formation of steel ingots for example. The hot top serves todelay the solidification of the feed metal or head metal containedwithin it so that molten metal can feed downwardly into the main bodyportion of the metal ingot to compensate for shrinkage of the ingotduring cooling, thereby preventing the formation of shrinkage cavitiesin the final ingot. In the particular embodiment illustrated, the hottop 10 includes a one-piece outside metal casing 11, with the lowerportion of the outside surface of the casing 11 being complementallyformed with respect to the inside walls of an ingot mold so that thelower portion of the hot top can extend down into the upper portion ofthe mold.

For the purpose of initially mounting the hot top on the lip of abig-end-up mold, an outwardly projecting flange 12 is formed at aboutthe midpoint of the casing so that the hot top can be set on a pluralityof wooden blocks spaced around the lip of the mold. The metal casing 11is also provided with a pair of trunnions 13 located about halfway upthe casing for use in inverting the casing, and another pair oftrunnions 14 for lifting the hot top.

In order to provide the thermal insulation required to delaysolidification of the molten metal in the hot top during the casting ofan ingot, the metal casing 11 is lined on the inside with a thin liner15 having low thermal conductivity. To provide the required thermalinsulation, the liner materialpreferably has a mean heat diffusivityvalue over the temperature range of C. to 1500 C. of below about 0.015centimeter-gram-second units. The term heat diffusivity is defined as\/KCp wherein K is the thermal conductivity of the material, c is thespecific heat, and p is the density. Suitable highly thermallyinsulating compositions are those described in the Davidson Patents Nos.3,072,981 and 3,123,878. The thickness of the liner can vary fordifferent applications, but in general it should be between about 0.5and about 1.5 inches.

If desired, a refractory bottom ring may be secured to the lower end ofthe metal casing 11 for the purpose of preventing the creepage of moltenmetal up behind the insulating liner 15 and to protect the lower end ofthe casing 11. In the illustrative embodiment, however, the bottom ringis obviated by use of an insulating liner which wraps around the lowerend of the casing, whereby the liner itself serves the purpose of thebottom ring. However, where it is desired to use a bottom ring insteadof a wrap around-type liner, a conventional sand ring may be used andheld to the casing by means of conventional spring clips. Also, aconventional wiper strip may be fitted over the lower outside corner ofthe hot top, extending entirely around the hot top with the upper end ofthe wiper strip bent outwardly to bear against the mold Wall to preventthe molten metal from rising in the gap between the hot top and themold.

As can be seen in the cross sections formed by the break away in FIGURE1, the lower inside corner of both the casing 11 and the liner 15 istapered so as to form a tapered top shoulder on the ingot. This taperedshoulder reduces overrolling during processing of the final ingot, andthus increases the yield from each ingot.

In a typical steel mill, ingots are cast in large batches, or heats.Thus, every time the ingots in a given heat are stripped from the moldsin which they are cast, an equal number of hot top casings must berelined before they can be reused in the casting of another heat ofingots. Of course, one of the necessary steps in the relining operationis removal of the residue from the previous liner; the liners usuallydisintegrate during the casting operation, but sometimes there is stilla residue of the used liner which clings to the hot top casing and mustbe removed therefrom before a new liner can be applied. This cleaningstep is not a novel feature in the method of this invention and can beaccomplished by any of the conventional cleaning means used for thispurpose.

The magnitude of the problem posed by the necessity of relining the hottop casings after each use will be readily appreciated when it isrecognized that hundreds or even thousands of ingots are cast every dayin a modern steel mill. As mentioned previously, the use of one-piecepreformed liner sleeves provides an efiicient means of relining the hottop casings between uses, but the space required to ship and store thesepreformed liner sleeves has mitigated against any widespread acceptanceof such a relining method in commercial casting of bigend-up ingots,especially in the larger mills where hundreds or thousands of hot topsmust be relined daily.

In accordance with this invention, the hot top casings to be relined arecontinually transferred to a fixed lining station where a perforatedforming tool is telescoped into each casing so as to form an annularcavity between the inside walls of the casing and the outside walls ofthe forming tool. A slurry comprising finely divided refractorymaterial, a fibrous material, and a liquid carrier is then fed into theannular cavity, the liquid carrier is Withdrawn through the perforatedforming tool to build up a composite layer of the fibrous and refractorymaterials in the annular cavity, and finally the forming tool istelescoped out of the casing and the layer of fibrous and refractorymaterials so that the layer forms a liner on the inside walls of thecasing. To complete the relining operation, the casing is thentransferred from the lining station to a drying station where the greenliner formed by the forming tool is dried sufficiently to permit thecasting of molten metal in the relined casing.

The relining method of this invention represents a significantbreakthrough in the hot topping art, permitting for the first timecomplete automation without any preforming operations whatever. Sincethe liner is completely formed in situ, the method not only can becarried out rapidly without any manual labor, but also does not re quireany shipping, storage, or handling of preformed liners. In effect, theliner is both formed and stored in the casing. Furthermore, since theliner is always in supporting engagement with the casing walls on whichit is formed, there is no need for the liner to be self-supporting.Consequently, the costly resins or other similarly expensive binderswhich are used to make the preformed liners self-supporting are nolonger required, thereby substantially reducing the raw material costsand providing a significant economic advantage over other reliningmethods. The method of this invention also permits elimination of allsupplemental retaining means, such as retaining rings and the like, tohold the liner in place because the in situ forming of the liner enablesthe use of selfretaining liner configurations.

Turning now to FIGURES 2 and 3 for a more detailed description of apreferred embodiment of the invention, a plurality of one-piece hot topcasings 11, from which the residue of the previously used liner hasalready been removed, are transported in seriatim by means of a rollerconveyor 20 to a fixed lining station including a casing table indicatedgenerally at 21. The casings 21 are inverted before they arrive at thelining station so that the wider end of the hot top opening is at the ofthe casing as it enters the lining station. The casing table 21 includesa central support plate 22 which is covered with a sealing gasket 23,and both the plate 22 and the gasket 23 are large enough in diameter tooverlap the edges of the casing opening. As a casing 11 enters thelining station, it rides over a plurality of rollers 24 which aremounted in vertically movable brackets 25 in a channel formed in thetable adjacent the main supporting plate 22. After the casing 11 hasreached a center position on the table 21, the rollers 24 are lowered bylowering the brackets 25 so that the casing comes to rest on the sealinggasket 23 on top of the central support plate 22.

After the casing 11 has come to rest on the sealing gasket 23 bylowering of the rollers 24, the entire casing table 21 is raised intotelescoped relation with a liner forming tool 26 which is mounteddirectly above the table 21 is axial alignment therewith. Raising of thetable 21 is accomplished by means of a hydraulic piston 27 mounted onthe top end of a vertical piston rod 28 which extends downwardly into acylinder 29 connected to a suitable source of pressurized hydraulicfluid. The forming tool 26 is complementally formed with respect to theinterior of the hot top casing 11 so that after the casing 11 and thetool 26 have been moved ino telescoped relationship with each other, anannular cavity is formed between the perforated out-side walls of thetool 26 and the solid inside walls of the metal'casing 11. Since thetool 26 and the casing 11 are complementally formed with respect to eachother, this annular cavity will be of substantially uniform width aroundthe entire circumference of the tool.

After the casing 11 and the forming tool 26 have been moved intotelescoped relationship, a slurry containing finely divided refractorymaterial, fibrous material, and a liquid carrier is fed into the annularcavity by means of a manifold assembly 30 extending around the top ofthe forming tool 26. The slurry is fed into the manifold assemblythrough a feed pipe 31 which conducts the slurry into an annularmanifold tube 32 having a plurality of inside ports 33 opening intocorresponding registering passageways 34 communicating with the annularcavity 35 between the casing 11 and the forming tool 26. In order toprevent any leakage of the slurry down along the outside walls of thecasing 11, an air filled sealing gasket 36 is mounted directly below theslurry passageways 3 4 for engaging the outer surface of the hot topcasing 11 as it is moved into telescoped relationship with the formingtool 26. Air is supplied to the sealing gasket 36 through a pipe 37connected to a suitable source of pressurized air.

As the slurry enters the cavity 35 from the manifold assembly 30, theslurry flows downwardly into the cavity 35, which is closed at thebottom by means of the sealing gasket 23 bearing against the bottom ofthe forming tool, with the carrier liquid being extracted through theperforated walls of the hollow forming tool 26 so as to build up acomposite layer of the solid fibruous and refractory material on theouter surface of the tool. The liquid extraction through the perforatedwalls of the tool 26 is effected by a pressure differential which may beachieved by several different means. For example, the slurry suppliedfrom the inlet manifold 30 is ordinarily under a certain feed pressure,and this pressure itself is sufficient in certain cases to force thecarrier liquid from the cavity 35 through the perforated walls into theinterior of the tool 26. In addiion, a vacuum may be drawn on the insideof the tool 26 so as to increase the pressure differential across theperforated walls and thereby enhance the extraction of carrier liquidtherethrough.

In accordance with one aspect of this invention, the liquid extractionprocess is facilitated by preheating the walls of the casing 11, beforeit enters the lining station, to a temperature above the boiling pointof the carrier liquid so that the liquid is vaporized as it contacts theinner walls of the casing. The resulting increase in pressure within thecavity 35, due to vaporization of the carrier liquid, tends to force thecarrier liquid inwardly through the perforated walls into the interiorof the forming tool. It will be appreciated that this preheating of thehot top casings will not usually require a separate heating step in acommercial operation, since the casings to be relined are already at anelevated temperature due to the heat absorbed from the molten metalduring the previous casting operation. Thus, in a typical commercialoperation, the casings reach a relatively high temperature during thecasting operation, but by the time a complete heat of ingots has beenstripped from the molds and the hot top casings have been cleaned of theused liner residue, the casings have usually cooled to a somewhat lowertemperature. This lower temperature is usually more than adequate tovaporize water, which is probably the most common slurry carrier liquidused in this type of operation. The upper limit on the temperature ofthe casings entering the lining station depends mainly on the charringor burning temperature of the other slurry ingredients. For example,when paper pulp is used as a fibrous ingredient in the slurry, thecasing temperature should not be above about 400 F. since temperaturesabove that level tend to char or burn the paper pulp.

It should be recognized that even though the residual heat in the hottop casings is normally adequate to provide the desired temperature inthe casings entering the lining station, it is still necessary toprovide a casing v preheater in order to heat new casings or casingswhich have cooled to room temperature during a shutdown. Of course, theprocess can also be carried out without any casing preheating, but thedrying times tend to be excessi-ve in such an operation.

As the carrier liquid is extracted through the perforated walls of theforming tool 26, the extracted liquid is collected inside the formingtool and discharged by gravity through a discharge port formed by anaperture 40 in the bottom of the forming tool 26 and registeringapertures 41 and 42 formed in the sealing gasket 23 and the centralsupport plate 22. The discharged liquid then enters an effluent chamber43 formed in the bottom of the table 21 and then on out through a wasteline 44. While the carrier liquid is being extracted through theperforated walls of the forming tool 26, the solid fibrous andrefractory material in the slurry are directed against the outer surfaceof the forming tool, with the fibrous material quickly building up arandom mat which acts as a filter to retain the finely dividedrefractory material within the liner cavity 35 while permitting thecarrier liquid to pass through into the interior of the tool.Consequently, a composite layer of fibrous and finely divided refractorymaterial builds up around the outer surface of the forming tool 26 untilit completely fills the annular cavity 35-, thereby forming a green"liner on the inner surface of the hot top casing 11. One of thesignificant advantages of the present invention is that the insulatingliner is for-med in situ on the walls of the hot top casing, so thatthere is no necessity for the liner to be self-supporting as in the caseof preformed liners for example. Consequently, the relatively costlyresins which are normally used to make the preformed linersself-supporting can be omitted from the slurry composition used in themethod of this invention. Moreover, since the lined casings are normallyused within a matter of hours after the liner has been formed, there isno problem of moisture pick-up in the casing, and thus again there is'no need for the costly resin which is used to minimize such moisturepick-up in preformed liners. The only essential ingredients of theslurry composition, other than the carrier liquid, are a finely dividedrefractory material and a fibrous material to form the filtering mediaon the perforated walls of the forming tool and to hold the compositelayer together. The fibrous material may be either organic, such aspaper pulp, or inorganic, such as asbestos fibers, or a mixture of bothorganic and inorganic materials. A suitable refractory material issilica flour, although many other finely divided refractory materialsknown in the art may be used in the place of, or in mixture with, thesilica flour. It is generally desirable to include at least a smallportion of binder in the slurry composition, but the method of thisinvention permits the use of inexpensive binders such as wheat flour andthe like rather than the costly resins used heretofore. Also, it will berecognized that many other materials may be added to the slurrycomposition for the purpose of providing the final liner with variousproperties which may be desirable in different applications. Forexample, certain exothermic materials may be included in the slurry toform an exothermic layer. Many other additives are well known to thoseskilled in the art and may be added as desired for different types ofcasting operations.

After the liner cavity 35 has been filled with the composite layer offibrous and refractory material, and sufficient carrier liquid has beenextracted therefrom to enable the green liner to maintain its integrityon the casing walls, the forming tool and the lined casing are movedrelatively away from each other, and the casing is transferred to adrying station to dry the green liner before it is used in the castingof another ingot. In order to break the green liner loose from the outersurface of the forming tool before the tool and the casing aretelescoped away from each other, compressed air is admitted into theinterior of the forming tool 26 just before the casing table 21 isretracted away from the forming tool 26. This compressed air applies abrief burst of pressure against the inner surface of the green liner,through the perforated walls of the tool, so as to break the green lineraway from the forming tool. Alternatively, other suitable means, such asa collapsible forming tool for example, could be used to break the lineraway from the forming tool before the tool and the casing are movedrelatively away from each other.

In order to transfer the lined casing away from the lining station afterthe table assembly 21 has been lowered to its fully retracted position,the transport rollers 24 are raised into engagement with the lower endof the hot top casing so as to raise the casing slightly off the sealinggasket 23. The casing is then transferred onto a continuation of theroller conveyor 20 which transports the casing and the green linertherein to a drying station where the green liner is dried sufficientlyto permit the casting of molten metal in the lined casing. The dryingstation may take the form of a conventional drying oven or any othersuitable drying means. It should be pointed out here that the length ofthe drying period is considerably shortened by preheating the hot topcasings upstream of the lining station, which of course, includes theuse of residual heat in the casings to provide the desired preheatingeffect. It should also be pointed out that the degree of drying requiredin the liners formed by the method of this invention is not as great asthe degree of drying required in preformed liners because there is nonecessity for the liners of this invention to be self-supporting sincethey are formed in situ.

In accordance with a further aspect of this invention, the inside wallsof the hot top casing are provided with a recess so that the linerformed in situ thereon projects into the recess to form a self-retainingliner. More particularly, the combination of the casing recess and thecomplementally formed liner projection serve to prevent the final liner,

which often shrinks somewhat during the final drying step,

from falling out of the casing when the casing is inverted .prior tobeing mounted on the ingot mold. Thus, the illustrative hot top casing11 is provided with a pair of peripheral recesses or grooves 51 and 52extending completely around the inner surface thereof. Consequently,when the insulating liner is formed in situ as shown in FIGURE 3, therecesses 51 and 52 form a part of the annular cavity 35 and thus thecomposite layer of refractory and fibrous material which fills thecavity projects into these recesses 51, 52. In other words, theinsulating liner is always complementally formed with respect to theinner surface of the hot top casing 11, and thus any recesses formed inthe inner surface of the casing will be occupied by complementallyformed projections on the liner which is formed in situ. In theparticular configuration illustrated, the two grooves 51, 52 areoccupied by complementally formed ribs '3, 54 which serve to preventaxial movement of the liner within the casing. Of course, axial movementof the insulating liner within the casing is not a problem as long asthe casing remains in the inverted position shown in FIGURES 2 and 3,but the casing naturally must be inverted at some subsequent pointbefore it is mounted on top of an ingot mold, and it is then that theretaining ribs 53, 54 serve to retain the liner within the invertedcasing. It will be recognized that the recesses formed in the innersurface of the hot top casings could be provided with many otherconfigurations, and these recesses will always result in the formationof a complementally formed projection on the insulating liner so as toretain the liner in place within the casing. For example, onealternative configuration would be the provision of a single groove inthe upper inside corner of the casing (the lower inside corner in theinverted position shown in FIGURES 2 and 3) so that a complementallyshaped flange would be formed on the resultant liner to prevent theliner from dropping out of the casing when it is subsequently inverted.These selfretaining liner configurations have the advantage ofelimihating the need for spring clips, or other supplementary deviceswhich are normally used to secure the liner within the casing, therebyeliminating the holes which must be formed in the hot top casing toreceive the spring clips and which tend to become clogged with metal.

An alternative embodiment of the present invention comprises forming thegreen liner on the outer surface of the forming tool before the casingand the tool are moved into telescoped relationship with each other. Inthis embodiment, the insulating liner is preliminarily formed on theperforated tool by the method described in Ednell Patent 3,066,069, orby any other suitable method. Then when the hot top casing 11 is movedinto position at the lining station and raised into telescopedrelationship with the forming tool, the green liner has already beenformed and it is simply a matter of pressing the casing against thegreen liner to complete the forming, and then blowing the green lineroff the forming tool onto the casing. The casing is then lowered awayfrom the forming tool in the same manner described above and transferredonto the drying station. This method has the advantage of permitting theuse of several forming tools at a single lining station so that a greenliner can be formed on one tool while the liner previously formed onanother tool is being transferred to a casing. Then for the next casing,the roles of the two forming tools would be reversed. 1n practicing thisembodiment of the present invention, the casing is raised until itpresses firmly against the green liner on the forming form so as toconform the liner to the exact shape of the casing while the liner isstill in a moldable condition. The casing is then lowered away from thegreen liner until it leaves a gap of approximately one inch or less tofacilitate the dislodging of the green liner from the forming tool by apuff of compressed air as described above. It has been found that thegreen liner can withstand the slight impact as it is transferred fromthe forming tool to the casing, even though no binder resin is includedin the liner composition.

As can be seen from the foregoing detailed description, the presentinvention provides an improved hot topping method and apparatus whichpermits reusable hot top casings to be quickly relined without thenecessity for shipping, packing, storing, and assembling preformedliners. This, of course, results in a number of attendant economicadvantages, such as elimination of shipping, packing, and storage costs,elimination of breakage problems, and the possibility of completeautomation with no manual labor whatever. This invention also permitssignificant reductions in the cast of the lining composition by virtueof the fact that the liner does not need to be self-supporting and,therefore, does not require any costly resin to bond the lineringredients together and/ or inhibit moisture pickup. This facilitatesformation of the liner because temperature critical resins are no longerrequired. Furthermore, this invention permits the elimination ofretainer rings because the liner can be formed in situ with aconfiguration which renders the liner self-retaining, simply byproviding appropriate recesses in the inner surface of the casing beinglined. Also, wiper strips can be embedded in the liner before it hasbeen completely dried thereby permitting elimination of the spring clipsor other supplementary devices which are used for retaining purposes.The inventive method also makes the dimensions of the hot top casingless critical because the liners which are formed in situ naturallyassume the same dimensions as the casing even though these dimensionsmay vary somewhat from casing to casing.

I claim as my invention:

1. Apparatus for forming heat-insulating liners in reusable hot topcasings for use on big-end-up ingot molds, said apparatus comprising thecombination of a fixed lining station, means for transferring aplurality of the hot top casings in seriatim to said fixed liningstation, a hollow perforated forming tool mounted at the fixed liningstation and complementally formed with respect tothe interior of the hottop casings to be lined, means at said lining station for receiving thecasings one at a time and relatively moving each casing and said formingtool into telescoped relationship with each other so as to form anannular cavity between the inner surface of the casing and the outersurface of the forming tool, means for feeding a slurry comprising afinely divided refractory material, a fibrous material, and a liquidcarrier into said annular cavity and means for Withdrawing the liquidcarrier through the interior of the hollow perforated forming tool so asto build up a composite layer of the fibrous and refractory material onthe outer surface of said tool, means for relatively moving the casingand the forming tool out of telescoped relationship with each other withsaid composite layer accompanying the casing, a drying station fordrying the liner within the casing sufliciently to permit the casting ofmolten metal in the lined casing, and means for continually transferringeach lined casing from said lining station to said drying station.

2. Apparatus for forming heat-insulating liners in reusable hot topcasings for use on big-end-up ingot molds, said apparatus comprising thecombination of a fixed lining station, means for continuallytransferring a plurality 0 of the hot top casings in seriatim to saidfixed lining station, a hollow perforated forming tool mounted at saidlining station and complementally for-med with respect to the interiorof the hot top casings, means for contacting the outer surface of saidforming tool with a slurry comprising a finely divided refractorymaterial, a fibrous material, and a liquid carrier and means forwithdrawing the liquid carrier through the interior of the perforatedforming tool so as to build up a composite layer of the fibrous andrefractory materials on the outer surface of said tool, means forreceiving each casing transferred to said lining station and relativelymoving said casing and said forming tool with the composite layerthereon into telescoped relationship with each other, means fortransferring said composite layer from the outer surface of said formingtool to the inner surface of said casing, means for relatively movingthe forming tool and the casing with said composite layer thereon out oftelescoped relationship with each other, a drying station includingmeans for drying said composite layer on the inner surface of saidcasing sufficiently to permit the casting of molten metal in the linedcasing, and means for transferring each lined casing from said liningstation to said drying station.

References Cited UNITED 'STATES PATENTS 1,637,532 8/ 1927 Oliver et al.162220 2,366,212 1/1945 Perry 162-397 2,881,680 4/1959 Spengler et al.9258 2,896,266 7/ 1959 Anthony 264269 2,942,319 6/ 1960 Anthony 16433 X3,066,069 11/1962 Ednell 162227 3,072,981 1/ 1963 Davidson 249-201 X3,120,684 2/1964 Gathmann 16433 X 3,216,069 1l/1965 Anthony 16433 X J.SPENCER OVERHOLSER, Primary Examiner.

EUGENE MAR, Assistant Examiner.

US. Cl. X.R. 164-33, 40, 187

1. APPARATUS FOR FORMING HEAT-INSULATING LINERS IN REUSABLE HOT TOPCASING FOR USE ON BIG-END-UP INGOT MOLDS, SAID APPARATUS COMPRISING THECOMBINATION OF A FIXED LINING STATION, MEANS FOR TRANSFERRING APLURALITY OF THE HOT TOP CASINGS IN SERIATIM TO SAID FIXED LININGSTATION, A HOLLOW PERFORATED FORMING TOOL MOUNTED AT THE FIXED LININGSTATION AND COMPLETMENTALLY FORMED WITH RESPECT TO THE INTERIOR OF THEHOT TOP CASINGS TO BE LINED, MEANS AT SAID LINING STATION FOR RECEIVINGTHE CASINGS ONE AT A TIME AND RELATIVELY MOVING EACH CASING AND SAIDFORMING TOOL INTO TELESCOPED RELATIONSHIPS WITH EACH OTHER SO AS TO FORMAN ANNULAR CAVITY BETWEEN THE INNER SURFACE OF THE CASING AND THE OUTERSURFACE OF THE FORMING TOOL, MEANS FOR FEEDING A SLURRY COMPRISING AFINELY DIVIDED REFRACTORY MATERIAL, A FIBROUS MATERIAL, AND A LIQUIDCARRIER INTO SAID ANNUAL CAVITY AND MEANS FOR WITHDRAWING THE LIQUIDCARRIER THROUGH THE INTERIOR OF THE HOLLOW PERFORATED FORMING TOOL SO ASTO BUILD UP A COMPOSITE LAYER OF THE FIBROUS AND REFRACTORY MATERIAL ONTHE OUTER SURFACE OF SAID TOOL, MEANS FOR RELATIVELY MOVING THE CASINGAND THE FORMING TOOL OUT OF RELATIVELY MOVING THE CASING AND THE FORMINGSAID COMPOSITE LAYER ACCOMPANYING THE CASING, A DRYING STATION FORDRYING THE LINER WITHIN THE CASING SUFFICIENTLY TO PERMIT THE CASTING OFMOLTEN METAL IN THE LINED CASING, AND MEANS FOR CONTINUALLY TRANSFERRINGEACH LINED CASING FROM SAID LINING STATION TO SAID DRYING STATION.